1. Choose the temperature of the hot water desired for the application
Suggested temperatures:
180 °F – “High temperature sanitizing” commercial dishwashers
140 °F – “Low temperature” commercial dishwashers
120 °F – Residential Whole House Tank Replacements; Commercial kitchen sinks including 3-compartment sinks
105 °F – All point of use handwashing including public handwashing; Standard shower temperature
60 °F to 90°F – Safety showers and eyewashes. Consult your Safety Engineer for a specific temperature.
Your desired outlet temperature: ________________________ degrees.
2. Find the temperature of the incoming cold water from the chart below
Map reflects general temperature zones, actual inlet temperature may be affected by local variations and seasonal changes.
Your cold water inlet temperature: ________________________ degrees.
3. Determine the total gallons per minute (GPM) demand
Typical flow rates:
| Residential or commercial hand sink | 0.35 or 0.5 GPM | |
| Residential kitchen sink | 1.5 or 2.0 GPM | |
| Bathtub | 4.0 GPM and above | |
| Residential dishwasher | 0.75 to 1.0 GPM | |
| 3-compartment sink | 2.5 to 3.0 GPM | |
| Commercial dishwasher | Contact Eemax Technical Support for assistance | |
| Shower | 1.5 to 2.0 GPM | |
| Washing machine | 1.0 to 1.5 GPM | |
| Whole-home replacement unit | 2.5 to 3.0 GPM and up |
Your total gallons per minute (GPM) demand: ________________________GPM
4. Determine the power required for your tankless electric water heater
Find the power required using the chart below:
The Rise in Temperature on the bottom of the chart is the inlet water temperature found on Step 2 subtracted from the desired hot water temperature found in step 1.
The Total Gallons per Minute (GPM) Demand on the left side of the chart is the GPM value as found in step 3.
The intersection of the Rise in Temperature column and the GPM demand row is the power required for your tankless electric water heater.
Find the appropriate Eemax model from the appropriate model family:
| Residential handwashing | LavAdvantage | |
| Public handwashing | AccuMix II | |
| Residential point of use | LavAdvantage or HomeAdvantage II | |
| Residential whole home tank replacement | HomeAdvantage II | |
| Commercial kitchens | ProSeries XTP | |
| Industrial safety showers | SafeAdvantage | |
| Industrial eyewashes and facewashes | Series 2 or Series 3 | |
| Commercial applications, such as hair salons or nail salons | ProSeries | |
| Industrial applications using Deionized or Reverse Osmosis water | Deionized |
Sizing for a tankless electric water heater needs to be accurate, but not precise. It is acceptable to use estimates or approximations for water temperature and flow rates. However, the more accurate the calculation, the better the performance of your tankless electric water heater in operation.
Undersizing your heater will cause hot water shortages during peak demand times; oversizing will result in unnecessary heater purchase expense and excessive installation costs.
Need more help? Click the button to contact our Customer Experience team or dial 475-377-3036 for more assistance.